oop_deriv

oop_deriv(coords, i, j, k, l=None, *, order=1, method='expansion', fixed_atoms=None, cache=None, reproject=True, expanded_vectors=None): 

LLM Docstring

Analytic derivative expansion of an out-of-plane coordinate for the i-j-k group (with j treated as fixed) with respect to the Cartesian coordinates.

Only method='expansion' is implemented. The out-of-plane value is formed as the difference of two dihedral-style derivatives (one holding the k vector frozen, one holding the i vector frozen), then reprojected onto the full coordinate set when reproject is set.

• coords: np.ndarray

  Cartesian coordinates, shape (..., N, 3)

• i: int

  first outer atom

• j: int

  central atom (held fixed)

• k: int

  second outer atom

• l: int | None

  optional reference atom (defaults to i)

• order: int

  maximum derivative order

• method: str

  derivative method ('expansion' only)

• fixed_atoms: Iterable[int] | None

  additional atoms to hold fixed

• cache: dict | None

  expansion cache

• reproject: bool

  whether to reproject the derivatives

• expanded_vectors: Iterable[int] | None

  which defining vectors to expand

• :returns: list

  the derivative expansion [value, d1, d2, ...]